1. Field of the Invention
The present invention concerns a method and a manipulator to separate bundle layers from a stack.
2. Description of the Prior Art
In many fields, goods bundles—that, for example, can be bound in containers or by packing means or packing aids (such as films)—and/or individual goods are combined into one or more bundle layers stacked atop one another for transport, storage, sale or the like. Individual goods and goods bundles are uniformly designated as bundles in the following.
Such compact bundle layers must be separated again at various points in the chain of the flow of goods, for example in order to consign multiple homogeneous bundle layers with the same bundles of mixed bundle series or layers.
To separate bundles, it is known (for example from DE 100 51932 A1) to subject the bundles to a speed jump at the transition between two conveyor belts. The downstream conveyor thereby exhibits a higher conveyor speed, such that the bundles are accelerated in the conveyor direction. DD 220 948 A1 discloses multiple speed gradations and synchronization around a corner in order to separate bundles into two directions at right angles to one another.
This type of separation decisively depends on the friction between the bundle and conveyor path. Such systems are therefore not only prone to error (for example due to vibrations, contamination or disadvantageous contact surfaces, such as PETs with star-shaped surfaces), but they also must normally be individually adjusted and calibrated differently depending on the bundles to be separated, which makes flexible logistics more difficult. In addition, bundles that are shifted on conveyors by guide edges transverse to the transport direction (for example that are collected into a row by channels tapering in the transport direction) tend to cant or jam at the guide edges.
From DE 201 08 401 U1, for example, it is known to separate bundles by means of automated manipulators. Position inaccuracies of the gripped bundles must disadvantageously be accepted, which is problematic for bundle layers delivered on conveyors due to the relative displacements of adjacent bundles that occur there.